1. Field of the Invention
The invention pertains to display systems and more particularly to the determination of the time interval between the start and end of a segment on the display.
2. Description of the Prior Art
Before start and end position signals for a symbol are coupled from a symbol generator to a display unit, the generator must receive a signal indicating that the prior symbol has been completed. In prior art CRT display systems circuitry coupled to the deflection amplifiers, that detect when the beam of the CRT has stopped, generate a signal at the conclusion of a symbol segment. This signal is coupled to the logic circuitry of the symbol generator, which waits until the signal is received before proceeding with the next symbol segment. When multiple redundant display units are driven from the same symbol generator, end signals must be received from all of the display units before the next symbol commands are issued. Logic must therefore be included in the symbol generator to prevent the delay of subsequent signal generation from an inordinate length of time due to a delayed or missing signal from a faulty display unit.
Other prior art systems incorporate waiting commands into the program controlling the symbol generator. This provides acceptable performance when the symbology is stationary. If the symbology, however, moves, or symbols are added or deleted to the middle of the program, the delay commands must be adjusted, a process requiring appreciable additional computation.
The prevent invention eliminates these problems by providing and end of slew signal that is related to the actual beam movement.